Research On Information Security In A Hierarchical Intelligent Control System

With the advent of the infomation age,the field of industrial control system has developed rapidly.The industrial devices are connected to each other through a fieldbus network,and the deployment is relatively scattered.Due to the lack of sufficient security of the fieldbus protocol,intruders can grasp the information security defects of the protocol to attack the system.Therefore,the research on the information security of fieldbus protocol is of great significance for the industrial infonnation security protection.Starting from the theory and practice,the paper studies and analyzes several popular fieldbuses in industrial control systems,namely Modbus/RTU,CAN,EtherCAT bus.Firstly,the Petri net formal modeling method is used to model and describe each fieldbus.Then reachability analysis method is adopted to analyze and verify the boundedness,reversibility and activity of the model to verify the correctness of the model.In view of the possible information security risks of the current fieldbus protocol,the Petri net is applied to formally describe the attack behavior.The experimental part adopts several fieldbuses of Modbus/RTU,CAN and EtherCAT to build a hierarchical intelligent control system,which will simulate the actual industrial control scene.The system is separated into decision-making layer,control layer and execution layer.Both of the communication between each layer and the communication between the upper and lower layers are realized.In order to simulate the behavior of the attacker.,several attack experiments were carried out,including the flood attack,eavesdropping and stealing data frames attack,man-in-the-middle attack.Those method of attacking are used to disrupt the normal operation of the system,then experimental results and effects are recorded.Lastly,a fieldbus monitoring system is designed,taking the CAN bus as an example,the system can monitor the status of CAN bus transmission data in real time,collect data at the same time,identify illegal data frames,and realize the security protection of control system informion to a certain extent.The focus of this paper is to analyze and study the fieldbus with the theory of Petri net,and analyze the information security risks of the bus system through attack experiments.I hope the content of this paper can provide theoretical reference for the design and information security protection of industrial control system.